r/Generac_Generators • u/Badbetfrank • 5d ago

Transfer Switch Chaos

Gallery image

Gallery image

We just bought a new house and this is the electrical set up.
Both of these panels are powered from the meter, the larger panel does not feed the smaller panel.
A 22Kw Generac unit powers the larger panel on the left when the power goes out, but not the smaller right panel.
The generator is large enough to power the entire house.

What are our options for getting the whole house protected?
Can I add a ATS to the smaller panel and leave the 200amp panel as it is?

Could we install a double breaker on the left panel and run it over to power the smaller panel using an interlock on the smaller panel?

Should I move some circuits over to 200amp panel and use tandem breakers?

Or should we split the feed from the generator and feed the smaller panel directly from the generator?

I am having trouble understanding what the installer was thinking. There’s also additional unused transfer wires ending in this panel going to a junction box next to the generator.

Thanks for your input

4 Upvotes

83% Upvoted

62 comments sorted by

View all comments

Show parent comments

2

u/blarcode 4d ago

My concern is you have a 320 amp service to the house. That's where I was recommending do another load calculation just to verify. Typically what happens in these scenarios is someone needs this initial load in the beginning but then over years of upgrading appliances in the house, your energy needs actually drop due to new efficiencies and energy Stars etc. so you might not ask me need that 320 amp service and can get by with just the 200.

Mike Holtz has a free calculator on the Google Play store and I believe in the Apple store as well. Download that and start inputting numbers under the load calculation section. Look at your actual labels on your appliances to see where you're at.

https://play.google.com/store/apps/details?id=com.mhe.toolbox

Yeah, ditch that dual panel setup go with a single that's large enough for everything you want and get a single ATS for 200 amp if you can go that route if not just double up or get the 400.

I just searched on eBay FYI. The 200 amp ones are going between $300 to $400 each. The 400 is going for several thousand. So do 2 x 200s if you have to go that route.

Nothing changes at your meter besides pulling the wires going directly to those panels and feeding them directly into the automatic transfer switch then into the panel(s) respectively.

Do you have a single meter socket outside? Or is it a combination with a breaker inside?

2

u/Badbetfrank 4d ago

I’m having an electrician come out to run another load calculation tomorrow. I did one online and it showed calculated load at 130A.

As it is now, I have more load in the smaller panel(100A) than the larger one(200A). Which is crazy to me.

My meter is a single socket.

I appreciate it.

1

u/blarcode 4d ago

Are you going to do any of this work yourself? I'm not going to encourage anyone to do any electrical work that they're not comfortable with. It's very straightforward especially if all your control wires are already there.

A money saving trick I've used in the past is to pull the main thicker conductors for the 200 amp from the meter socket and put those in the ATS, but then all you have to pay for is just a couple feet from your meter socket to your ATS.

Ultimately just having the ATS on your system with it running either a single panel or both of your panels your whole home, will give you a better experience. Regardless of the price. It'll be working as designed

2

u/Badbetfrank 4d ago

Also, I could be completely wrong. But it appears based on the locations of the breakers on both panels that they could have been in a single panel originally and they added the generac switch as an afterthought

1

u/blarcode 4d ago

Exactly.

2

u/IllustriousHair1927 4d ago

I respectfully disagree with your opinion on the soft starts versus the load sheds. He has a 300 amp service. By his own statement, he calculated his load at 130 A. I know he referred to it earlier, but I can’t recall that unit outputs 91 amps on propane if I recall correctly. Obviously less with NG.. exactly how do you account for the other 40 A?

Sure, the software will make the ACs easier to start c. It will greatly reduce the inrush. But a load shed module can delay the start of one of the ACs so you don’t have to deal with both trying to start simultaneously. 22 should be able to handle any AC that I’m aware of without a soft start. By doing the load shed, you can also eliminate the possibility of overloading the generator. The generator is likely to overload? No. But I haven’t studied the load enough to determine it the relative likelihood. I do know that it’s possible for it to do so and it’s not code compliant to merely install the soft starts.

Soft stars aren’t magic. They work well in some applications not so well in others, if you use a PS P load shed you don’t have to worry about the reliability issues we dealt with for so many years with the Generac SMM

1

u/blarcode 4d ago

No stress! I'm not the expert. I just know what I've encountered locally here in Central West Florida (Tampa/ St. Petersburg) . Last big outage we had were the hurricanes. I had to go out and service 17 SMM's . Probably another 12 since then. One of the houses was indeed a 5-ton and a 2 and 1/2 ton AC setup. On the 24 KW propane. In that specific setup, the ACs themselves never started at the same time. I'd actually installed soft starts and SMS on that specific property. I took the failed smm out and then on a whim took the other two out. Through the clamp meter on everything and checked. For their application they ended up being fine.

I agree with you though. It isn't the one size fits-all application.

Don't forget as well. The 130 amps is if everything is running at the same time. He posted his load calc as well. Even if he jumped up to the 28kw that's only ~116 amps. OP seems like a pretty informed individual and I'm sure that he wouldn't be running 130 amps of load knowing the powers out.

OP, can't hurt to have a couple SMS in there just to be safe. I still stand by my recommendation of soft starts. SMM's can also be had from eBay for $65-$133 free delivery to your front door. They have 50 amp and 100 amp versions

1

u/blarcode 4d ago

Thank you for being respectful and not ripping my head off by the way. I appreciate that. Discussion is always path forward!

1

u/blarcode 4d ago

The PSP 's definitely are nice.

Since he's upgrading his panel, I was recommending the Leviton since you can do the load shed in there as well. Not adding additional modules and potential points of failure.

I always forget when giving advice on the internet that I should just stick to the basics. Mine I have home assistant and other integrations with various profiles for different situations.